The present invention generally relates to intravascular devices. More specifically, the present invention relates to reinforced intravascular catheters.
Intravascular catheters are used in a wide variety of relatively non-invasive medical procedures. Such intravascular catheters may be used for diagnostic or therapeutic purposes. Generally, an intravascular catheter allows a physician to remotely perform a medical procedure by inserting the catheter into the vascular system of the patient at a location that is easily accessible and thereafter navigating the catheter to the desired target site. By this method, virtually any target site in the patient""s vascular system may be remotely accessed, including the coronary, cerebral, and peripheral vasculature.
The distance between the access site and the target site is often in excess of 100 cm. The inside diameter of the vasculature at the access site is often less than 2 cm, and the inside diameter of the vasculature at the target site is often less than 0.5 cm. Accordingly, intravascular catheters must be relatively long and thin. Furthermore, in order to navigate through the patient""s tortuous vascular system, intravascular catheters must be very flexible. It is also desirable that intravascular catheters be relatively soft in order to minimize the probability of damaging vascular tissue.
Intravascular catheters typically have a radiopaque portion and are guided through the patient""s vascular system with the assistance of x-ray fluoroscopy. In this manner, a physician may manipulate the proximal end of the catheter and fluoroscopically monitor the corresponding movement of the distal end of the catheter. As such, it is desirable that intravascular catheters be sufficiently radiopaque along their length and particularly at their distal end such that the physician is able to clearly monitor the progress of the catheter as it is being advanced from the vascular access site to the vascular target site.
After the intravascular catheter has been navigated through the patient""s vascular system with the distal end thereof adjacent the target site, the catheter may be used for various diagnostic and/or therapeutic purposes. Frequently, diagnostic and therapeutic techniques require the infusion of fluids through the catheter. For example, it may be desirable to inject radiopaque contrast media through the catheter to provide enhanced fluoroscopic visualization for diagnostic purposes, or to inject pharmaceutical solutions (i.e., drugs) to the target site for therapeutic purposes. In order to maintain a fluid path, it is desirable that intravascular catheters be sufficiently resistant to kinking. In addition, because such fluids are delivered under pressure, it is also desirable that intravascular catheters be sufficiently resistant to bursting.
To satisfy some of these desirable features, prior art intravascular catheters have utilized a reinforcement structure such as a braid or coil disposed between an inner lubricious tubular layer and an outer flexible tubular layer. A braid reinforcement structure offers high resistance to bursting and improves the connection integrity between individual shaft segments. However, braid reinforcement offers limited resistance to ovaling, which is a precursor to kinking. A coil reinforcement structure, by contrast, provides adequate resistance to ovaling and kinking, but does not sufficiently enhance the connection integrity between individual shaft segments.
The present invention overcomes these disadvantages by providing an intravascular catheter that exhibits the combined features of superior flexibility, softness, radiopacity, durability, high burst strength, and oval/kink resistance.
An intravascular catheter in accordance with one embodiment of the present invention includes an elongate shaft having a proximal region, a distal region and a lumen extending therethrough. The proximal region of the shaft includes an inner lubricious polymer layer, a reinforcement layer and an outer layer. The reinforcement layer comprises a braid having at least one metallic member and a plurality of polymer members wherein each polymer member comprises a plurality of monofilaments. The monofilaments may be made of LCP having a substantially circular cross-section and may be unfused or fused together. The monofilaments may be arranged side-by-side to collectively define a flat cable that may be twisted along the length of the shaft. The metallic member(s) may be made of a highly radiopaque material. The catheter may further include a longitudinal member extending along the reinforcement layer. The longitudinal member may also comprise a plurality of longitudinal monofilaments made of a polymer, such as LCP. The distal region of the shaft may include a radiopaque marker band surrounding the reinforcement layer and an atraumatic tip layer surrounding a portion of the radiopaque marker band and a portion of the reinforcement layer. The tip layer may extend distally beyond the distal ends of the inner layer and the reinforcement layer to form an atraumatic soft distal tip.
The brand reinforcement provides high burst strength and durability. The polymer members of the braid provide enhanced flexibility and softness, and the metallic members(s) of the braid provide enhanced radiopacity and resistance to ovaling and kinking. These combined features are not found in the prior art.
An intravascular catheter in accordance with another embodiment of the present invention includes an elongate shaft having a proximal region, a distal region and a lumen extending therethrough. The proximal region of the shaft includes an inner lubricious polymer layer, a reinforcement layer and an outer layer. The outer layer includes a proximal portion made of a first material having a first durometer, and a distal portion made of a second material having a second durometer less than the first durometer. The reinforcement layer comprises a braid having one or more metallic members and a plurality of polymer members wherein each polymer member comprises a plurality of monofilaments. The distal region of the shaft includes a radiopaque marker band surrounding the reinforcement layer and an atraumatic tip layer surrounding the radiopaque marker band and the reinforcement layer. The tip layer is made of a third material having a third durometer less than the second durometer. The tip layer includes a distal portion that extends beyond the distal ends of the inner layer and the reinforcement layer to form an atraumatic soft distal tip.